1. Field of the Invention
This invention relates to fiber optic arrays, and to the use thereof in an image forming station in a photocopy device.
2. Description of the Prior Art
For a number of years various investigators have contemplated ways of eliminating troublesome lenses and mirrors typically found in photocopy devices for conveying light reflected from a graphic original (and which is, therefore, capable of forming an image of said original) onto a light sensitive receptor sheet at which the image is formed. One approach frequently encountered, for example, is to contact expose, directing light either through the backside of the original or receptor sheet. Another approach, more germane to the present invention, has been to suggest an array of coherent optical fibers having a high index core and a low index clad for conveying a line of light reflected from the original onto the receptor sheet, while simultaneously traversing the original and receptor sheet past opposite ends of the array such that the original is scanned and a corresponding scanned image is formed on the receptor sheet.
Despite the relatively long time such a concept has been recognized, photocopy devices embodying such an optical configuration have not been commercialized. It is believed that prior concepts have suffered from a common inability to provide a commercially viable structure by which sufficient quantities of light could be directed onto the original proximate the end of the array of fibers. For example, U.S. Pat. No. 3,125,013 (Herrick et al) discloses a reflex copying apparatus which utilizes a complicated fiber optic array both for transmitting light reflected from a graphic original onto a receptor sheet and for conveying illuminating light from light sources positioned on both sides of the array onto the original. GB Pat. No. 1,183,973 also depicts a similar scheme of alternatively positioned fibers for illumination and image transmission. U.S. Pat. No. 3,175,481 (Lahr) discloses a document copier in which a single row of optical fibers is positioned in a linear plane extending between and normal to the direction of movement of a document and receptor sheet. In that apparatus, illumination of the document appears to be provided by tubular light sources separately positioned on each side of the fiber array, the light being focused into a single line of light extending transversely across the document and adjacent the array by additionally positioned converging lenses. Such a cumbersome assembly, which still requires the use of lenses has not, apparently, been able to provide advantages over the optical systems used in conventional, lens oriented, copy machines.
A similar assembly is also depicted in U.S. Pat. No. 3,232,201 (Frank and Michel), but in which the lens used to focus the light onto the document is replaced by a prism. In U.S. Pat. No. 3,398,669 (Hicks) such optical concentrating elements are omitted; however, separately positioned tubular light sources on both sides of an optical fiber array are depicted.
More recently, the Minolta Corporation has disclosed a prototype of a photocopier which utilizes an array of graded-index fibers such as that disclosed in U.S. Pat. No. 3,658,407 (Kitano). Other patents, including U.S. Pat. Nos. 3,936,672 (Tanaka), 3,947,106 (Hamaguchi et al), 3,955,888 (Kakiuchi et al), 3,981,575 (Tanaka et al) and 4,068,936 (Kushima et al) may relate to various aspects of that copier.